Machine for generating and cutting threads and the like



July 10, 1923.

E. w. MILLER MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE Filed Nov. 15 1921 14 sheets-sheet l Jul 10, 1923. 1,461,219 E. W. MILLER MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE Filed Nov, 15 1921 14 sheets-sheet- 2 July 10, 1923.

E. W. MILLER MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE Filed Nov. 15. 1921 14 sheets-sfiet- 4 g 90K 2 v f 2 IIIII July 10, 1923. 1,461,219 E. w. MILLER MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE Filed Nov. 15 1921 14 sheets-sheet 5 July 10, 1923. 1,461,219

. E. W. MI LLER MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE FiledNov. 15 1921 14 shegts-sheet 6 July 10, 1923. 1,461,219

LE. w. MILLER v MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE July 10, 1923.

E. W. MILLER.

MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE Filed Nov. 15,, 14 sheets-sheet 8 July 10, 1.923.

E. W. MILLER MACHINE FOR GENERATING AND CUTTING- THREADS AND THE LIKE Filed Nov. 15 1921 14 sheets-sheet 9 July 10, 1923.

E. W. MILLER MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE 14 sheets-sheet- 10 Filed Nov. l5 1921 July 10, 1923.

E. w. MILLER I MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE Filed Nov. 15. 1921 14" sheets-shee'c- 11 July 10, 1.923. 1,461,219 E. w. MILLER MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE Filed Nov, 15', 1921 l4 sheets-sheet 12 ykgfl/O July 1 O, 1923.

E. W, MILLER MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE Filed Nov. 15.

1921 14 sheets-sheet 15 Jur 10, 1923.

- E. W. MILLER MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE Filed Nov. 15. 1921 14 sheets-she et l4 Patented July 10, 1923.

UNITED .S-TATES PATENT OFFICE.

EDWARD W. MILLER, OF SPRINGFIELD, VERMONT, ASSIGNOR TO THE FELLOWS GEAR SHAPER COMPANY, OF SPRINGFIELD. VERMONT. A CORPORATION OF VERMONT.

MACHINE FOR GENERATING AND CUTTING THREADS AND THE LIKE.

Application filed November 15, 1921. Serial No. 515,291.

To all whom. it may concern:

Be it known that I, EDWARD W. MILLER, a citizen of the United States, residing at Springfield, in the county of WVindsor and State of Vermont, have invented new and useful Improvements in Machines for Generating and Cutting Threads and the like, of which the following is a specification.

The present invention relates to generatin and cutting machines.

ts object is to produceamachine of this nature capable of generating and cutting in a continuous operation threads in worms, hobs, taps'and the like.

A further object is to provide such a machine with such capabilitiesof adjustment and substitution of different cutting tools for one another that by-selection of an appropriate cutter and proper adjustment of the relative generating travel between the cutter and work, threads of any desired pitch and profile, and other work pieces of various undulato'ry forms of profile, maybe produced, Within practicable limits as determined by the size and other conditions of the machine.

outline consisting of one or more rises and depressions. l/Vithin this definition the profile of the thread of any shape is an undulatory line.

Still another object is to combine with means for producing the effects above 'referred to means for causing the cutter to cut the work piece in such a way as to back off or-relieve those parts of'the work piece vention for which Iclaim protection herein are explained with reference to a specific machine which is described in detail in the following specification and illustrated in the drawings forming a part thereof. In said drawings, I

Figure 1 is a front elevation of the machine referred to.

Figure 2 is a plan view of the machine. Figure 3 is an elevation of the left hand end of the machine.

Figure 4 is a right hand end elevation. Figure 5 is a horizontal section, the plane The term undulatory as used- .in this specification in connection with profile work pieces is intended to include any of which is indicated by the line 5-5 of Figure 4.

Figures 6 and 7 are vertical longitudinalsectional views taken on planes indicated respectively by line 66of Figure 3 and line 7-7 of Figure 4. These two figures together show. substantially the entire machine in longitudinal section.

Figure 8 is a cross section on the line 88 of Figure 1.

Figure 9 is a longitudinal section of the cutter carriage, the plane of which section is indicated by line 99 of Figure 10.

Figure 10 is a cross section of the cutter carriage showing the oscillating head partly in elevation and partly in section.

Figure 11 is a sectional view enlarged showing the parts out by the line 11-l1 in Figure 1.

Figure 12 is a vertical section on line 1212 of Figure 11.

Figure 13 is'a horizontal section on line 13-13 of Figure 12.

Figure 14 is a rear elevation of the right hand end of the machine.

Figure 15 is a fragmentaryview showing a part of the right hand end of the machine in elevation on a larger scale than Figure 4.

Figure 16 is a detail view'partly in section and partly 'in elevation offthe mechanism by which the cutter is caused to take a second or finishing cut.

Figure 17 is a plan View of a part of this mechanism.

Figure 18 is a detail sectional view taken on line 1818 of Figure 17 Figure 19 is a cross section showing the adjusting means for regulating the depth of cut and the means for setting the cutter to take a finishing cut.

Figures 20 and 21 are respectively a front elevation and a plan view of a part of the left hand end of the machine equipped with means for generating relief in the work piece, when such piece is a cutting tool such as a hob or the like.

Figure 22 is a partial cross section and partial elevation of the form shown in Figscrew in opposite di- I 'as being carried by a mandrel 3 supp tion obtains the result of generating desired forms in a thread, or equivalent character of work, by causing not only a feed to take place between the work piece and the cutter at a rate correspOndin to the pitch of the thread being cut, but a so by causing a rolling motion of the cutter and work, one relatively to the other, which is like the rolling motion occurring between conjugate or coinplemental gear elements similar in contour to the cutter and work respectively. The cutting edge of the cutter then has an outline similar to the tooth forms of a gear' conjugate to the longitudinal section of the work. For instance, a worm having a straight sided thread is in longitudinal section similar to a rack of which the sides of the teeth are straight, and for cutting such a thread the cutter used 'has the form of an involute spur gear at its cutting edges. For generating threads with other than straight sides, the curves of the teeth on the cutter are otherwise formed conjugate to the desired thread shape. In other respects the cutter is formed according to approved shop practice to have sufficient strength and to make contact with the work only at its cutting edges. Usually the cutter teeth will be helical elements corresponding to the helix angle of the thread being produced, but'they need not always have this form, especially in cases where the thread angle being produced is small.

In the particular embodiment of the invention herein illustrated and described, the machine is shown as equipped for cutting a straight sided thread of steep'pitch, and the cutter illustrated is one in which the teeth are helically arranged and have the outline of involute spur gear teeth at their cutting ting edges to give proper clearance.

In the drawings the work piece is designated by the numeral 1 and the cutter by the numeral 2. The work is shown-in Figure 5 orted. at its opposite ends by a headstock'4 and tailstock 5; that end which is supported by the headstock being connected with a work spindle 6 in any approved way so that it may be rotated by said shaft. w

The cutter is secured to the end of the cutter spindle 7, (see particularly Fi' ure 8) which is mounted rotatably in a hea 9' carried by a slide 10. The slide is adapted to V move endwise on guideways 11and '12 on the fixed machine base 13. The head and slide togetherfo'rm the cutter carriage, and the direction in which such carriage is able to move is determined by the guideway 11, which is formed as a rib embraced between a shoulder 14 and an adjustable gib 15 on the carriage.

Driving and ceding mechanism.ln this particular mac ine the cutter acts on the upper side of the work and the latter is rotated so that its upper side turns toward the cutter. The cutter carriage travels from left to right and the cutter is at the same time rotated in counter-clockwise rotation as viewed from the front of the machine; that is, when cutting right hand threads. Attention is directed to Figures 1 to 8 inclusive and the diagram Figures 23, 24, and 25 for illustration of the gearing applied for this purpose. The cutter carriage is moved endwise by a lead screw 16,'and the cutter 1s rotated by a long worm 17 in mesh with a worm wheel 18 which is engaged with the cutter spindle 7 through the medium of a sleeve 19 (Figure 8), on the outside of which the worm wheel is mounted and connected by a key 20, and inside of which the spindle has a splined engagement by means of a feather 21. This lead screw, this Worm, and the work spindle are all rotated by the same pulley 22 which is driven by a belt. 23 is a loose pulley beside the pulley 22 adapted to receive the belt when the machine is idle. Pulley 22 is connected with a sleeve 24 (Fig. 6) which surrounds the shaft extension 17 of the worm 17 and has a splined engagement therewith by means of a key or feather 26. Thus the worm is rotated by means which permits of an endwise movement being given to the worm at the same time. The gear 27 is keyed on the sleeve 24 and drives the work spindle 6 through the drive gears 28 and 29 and change gears 30 and 31 (see Figures 3, 23, 24, and 25). The proper 7 number of teeth in the cutter and number of threads to be produced in the work, and also the number of teeth in the worm wheel 18 and threads in the worm 17, by applying change gears 30 and 31 of the proper ratio.

The lead screw 16 is driven by an extension of the same gear train consisting of a gear 32 onthe work spindle, a gear 33 (in mesh with 32) and a connected pmion 34, on

an intermediate stud 35; a gear 36 in mesh with 34 and keyed to a short shaft 37, a shaft 38, and a pair ofchange gears 39 and 40 on the shaft 38 and lead screw 16,'respectiyely. A reversinggear mechanism is interposed between the shafts 37 and 38 in order that the direction ofrotation of the lead screw may be reversed and the carriage returned to its starting point, without reversing the other mechanism. This reversing gear consists of a bevel gear 41 fast to shaft 37, a bevel gear 42 loose on the shaft 38, an intermediate bevel gear 43 in mesh gear 42- said clutch sleeve being splined to the sha 38.

Both the work spindle and lead screwmay be driven in the reverse direction to cut left hand threads in the work by shifting the gear 28 of the train previously described into mesh with the reversely rotating gear wheel 46, which is mounted on a stud 47, in mesh with the gear 27 and continuously rotated thereby. In order that gear 28 may be thus shifted it is mounted eccentrically on a shaft 48 (Figures23 and 24) which is adapted; to be oscillated in its fixed bearings by a crank 49 (Figures 1 and 2) havinga locking pin 50. The change gear 30 and its associated gear 29 are mounted upon a quadrant 51 (Figure 3) which is adapted to. swing about that 'zone of shaft 48 which is concentrio with gear 28, and is secured by a clamp screw 52. U

The entire gear train 27-36 is mounted at the left hand end of the machine in a casing 53 having a detachable cover; and the change gears 39 and 40 are mounted at the right hand end of the machine in a casing 54 also having a detachable cover, whereby that due to the rotational movement of the.

worm. Rotation of.the worm alone (the feed movement of the carriage being disregarded) .gives to the cutter .the same character of rotation as that. of a worm wheel turning on a stationary axis in mesh with a rotating and otherwise stationa' worm of the same pitch as the work. T e rotation of the cutter, due to the endwise relative motion between carriage and worm, compounded with its displacement bodily due to the travelof the carriage (rotation of the worm being now disregarded), causes the cutter to roll along the work in the same manner as a pinion having the same .form as the cutter would roll in mesh with a stationaryrack having teeth conjugate to those of such pinion. The resultant motion which actually takes place (with respect to the cutter and work piece) is compounded'of all the single motions just, described, and e-nables the cutter to cut a thread offull required depth in one pass across the work. The amount of stock removed by each cutter tooth is determined by the speed of carriage travel, and may be regulated as required by proper selection of the change gear pair 39-40. That component .of the cutter rotation due to the rotation only of the worm causes the cut made to be helical; while the additional rotation, and translative movement, of the cutter due to relative endwise travel of carriage to worm-causes the operation to progress along the work and the sides of the thread to be generated truly conju-' gate to the tooth curves of the cutter. This last mentioned component of the cutter movement maybe called the generative travel of the cutter. I

Compensation for difference in. diameter of cutter and d'rz'm'xng worm wheel.Prefer-- ably the worm wheel 18 which drives the cutter rotatably is larger in diameter on its pitch circle than is the cutter, from which it follows that'if the worm 17 had no endwise movement the cutter would destroy the work on account of its generative travel being slower than the displacement travel of the carriage. Therefore the worm is moved endwise oppositely to the movement of the carriage whenever the latter is set in motion. To obtain this result a rack 55 is mounted at the rear of the machine (Figures 2, 3, 4, 14, 15, and 25) in a fixed guide 56 and is connected with the carria e slide by means of a tongue 57 secured to t e slide and entering a notch in the rack. The teeth of this rack mesh with a gear wheel 58. secured to a transverse shaft 5 9, on which there is also secured a gear 60, which-is one of a pair of change gears. The other change gear 61 of this pair is mounted on a shaft 62 which crosses from oneside' to the other of the machine and carries on its other end-a gear 621 meshing with a gear 63 on a shaft 64. Gears 621 and 63 are also change gears. Shaft 64 carries a gear 65 in mesh with a rack 66 which is formed on a sleeve 67 surrounding the extremity -17 of the worm shaft and in which the latter has a rotative bearing. This rack sleeve 67 is retained in position by a thrust shoe68 fastened to the rigid casing at the end of the machine in a manner such that the rack sleeve may be moved endwise through it. By proper selection of the change gears 6061 and 621 63 justable angularly about the axis of the worm 17 in order that it may cut to the proper depth in work pieces of different diameters; and it is also adjustable in the direction of its axis to bring the plane of its end face, in which the cutting edges lie, radial to the work piece, or in such other predetermined position as may carry out the best practice in cutting. The worm wheel 18 is also adjustable in and out with respect to the worm 17 in order to take up looseness and obtain its proper mesh with the worm, For an explanation of these adjustments attention is called to Figures 6 to 10 inclusive. The cutter head 9 is provided with hollow trunnions 69 and 70 which occupy bearings 71, 72 in the slide 10 and are retained by bearing caps 78 and 71. These trunnions are coaxial with the worm 17 and furnish the bearings in which the latter turns. Thus the cutter head is able to oscillate about the worm and the distance of the cutter from the axis of the work spindle is changed by so doing. In order to set the cutter at a given distance from this axis, there is provided a bar 75 (Fig. 19) which is movable endwise in a guideway 76 in the cutter head and carries an anti-friction roll 77 which makes contact with an abutment or stop' 78, such stop having in this machine the form of a cam whereby it performs an additional function presently described. The bar or slide 75 is threaded and meshes with internal threads in a sleeve nut 79 on which is fastened a wheel 80 for rotationmanually. This sleeve nut is held in place by a bearing sleeve 81 which is secured within the guidway. A plunger 82 (Fig. 10) confined and movable endwise in a second guideway 83 is pressed by a spring 84 toward a stationary abut-- ment 85 on the slide, and serves to hold the roll 77 against the abutment 78 and to maintain the cutter in its operative relation to the work;

Adjustment of the cutter head around the axis of the worm changes the angle which the cutting face of the cutter makes with, the nearest radius of the work spindle. Endwise adjustment of the cutter spindle to bring the cutter plane radial to the work, is accomplished by rotation of a stem 86 which is threaded at its inner end and is screwed into a complemental threaded socket 87 in the end of the spindle. This stem is rotated the stem.

When any adjustment has been given to the cutter spindle 7 in the manner described, such adjustment is locked by expanding the split end of the threaded stem 86 against the walls of socket 87 by means of an expanding plug 97 on the inner end of. a rod .98 on which is a nut 99 abutting against the end of The key or feather 21 between the cutter spindle and bearing sleeve permits such endwise adjustment of the spindle as may be required, without destroying the rotation-transmitting connection between the spindle and its driving worm wheel.

To obtain an exact adjustment of the penetration and closeness of fit between the threads of worm 17 and the teeth of wheel 18, the wheel and bearing sleeve 19 are mounted eccentrically in a tubular holder 100 which is rotatable within the cutter head 9. This "holder has teeth on a part of its exterior as indicated at 101 in Figure 9, and engaged with these teeth is an adjusting worm 102 of which the shank 103 protrudes from the cutter head and is adapted to be engaged and turned by a wrench.

Finishing cut feed.-Although a thread may be cut to full depth in one pass, nevertheless it is preferred, in the interest of accuracy and smooth finish, to cut the thread nearly but not quite to its final width and depth in the first pass of the cutter ,over the work, and then toreduce it to finished size by a light cut taken in the revers travel of the cutter.

presently described in feeding the cutter to the proper depth for the finishing cut. This cam then has a single step 104 and is cirwith roll 77, and the adjuster 75 is so set that the preliminary or roughing cut will be less deep by an amount equal to the height of the cam step 104 than that needed for the finished .Work. Cam 78 is mounted on a shaft 105 which is rotatable in bearings in the carriage slide 10 and is heldso as to move endwise with the latter. It is additionally supported by a bearing 106 in the stationary frame (Fig. 17) with respect to which it is both rotatable and endwise movable. A collar 107 is mounted on this shaft and carries a projection 108 adapted to be acted on by two stationary abutments 109 and 110, respectively, on a bracket 111 which is secured to the machine frame. When the cutter carriage reaches the end of the first traverse, the projection 108 engages the abutment 109 and is thereby so displaced that the high part of the cam 78 is moved away from the roll 77 and the low part of the cam brought into position. Thus the cutter is automatically fed into the work,

The abutment cam 78 (Figs. 16-19) cooperates with other mechanisms or arranged and movable in any other manner.

Gutter ca/M'iage reversing mechanism.- The automatic return of the carriage after completion of the first cut is efiected automatically by shifting of the clutch 44 from engagement with the gear. 41 into engagement with the gear 42, whereby the direction of rotation of the lead screw 16'is reversed. The clutchshifter 45 is moved to that effect by mechanism shown in Figures 1, 5, 11, 12, and 13. This clutch shifter is pivoted on a stud 112' fixed on a bracket 113 (Figure 11) and has an arm 114 coupled by a pin and slot connection with a block 115 which slides on a bar 116 fixed in a housing 117 secured to the frame of the machine. In the housing is mounted a rock shaft 118 carrying an arm 119 on which is fixed a stud 120 and to't-he opposite sides of which are pivoted swinging arms 121, 122, each alsoconnected to said arm by a spring 123. The stud 120 projects between two dogs 124 and 125 which are pivoted in the housing 117 at opposite sides of the sliding block 115. The swinging arms are also pressed by the springs 123 against opposite sides of another part of this block. Th'edog 124 has one locking abutment126 and the dog 125 has two such abutments, 127 and 128. Figure 12 shows this mechanism in the neutral position, wherein the abutment 128 engages the block and abutment 126 rests on the block. If now the arm 119 should be moved to the right for instance, the'stud 120, bearing on an inclined surface 129 of the dog 125 would raise the latter so as to clear the abutment 128 of the block, and the spring pressed arm 121 would then be free to move the block to the right, which would result in coupling the clutch 44 with the gear 41-, the condition required for the first traverse of the machine. The dog 124 then falls so as to lock the slide in this position by means of abutment 126. If now the arm 119 is moved in the opposite direction the dog 124 is first released from the; slide, and then the latter is moved by the spring pressed arm 122 to shift the clutch into re verse driving position, and it is locked in this position bv the shoulder 127.

A handle 130 is made fast to the rock shaft 118, bywhich the movements of the arm 119 just described may be carried out manually; and there is also secured to the rock shaft, as part of the arm 119, a forked arm 131, the fingers of which embrace stud 132 on an endwise movable bar. 133. bar carries separate trip pins 134 betweenwhich are trip dogs 135 on the carriage slide. There are two of such dogs seated in a groove 136 on the edge of the slide and thereby adapted for adjustment to determine the times at which automatic reversal and arrest of the carriage willtake place.

It will now be understood that if the carriage is set in motion by that movement of the handle 130which moves the arm 119 to the right from the neutral position shown in Figure 12, the carriage will be fed from left to right until the, right hand trip dog strikes the right hand trip pin, Then bar 133-will be moved to the right, am 119' is moved to the left, and the feed control clutch moved'to the right with the efi'ect of. reversing the direction of carriage traveLi On return to the starting position, the left hand trip dog strikes the left hand trip ph and causes the control switch to be shifted into neutral position, because as soon as the locking shoulder 127 has been disengaged from the slide 115 the latter is moved by the spring arm 121 only to the point at which it is arrested by shoulder 128, which point is in the neutral position.

Operation-It may be assumed first that the machine is prepared for cutting a thread of a certain pitch ina work piece of a certain diameter by the application of the cutter and change gears appropriate to the particular case. If the feed controlling clutch 44 is in the neutral position, starting the machine by shifting the driving belt over to the fast pulley 22 will simply cause the cutter and the work p ece 'to rotate at their appropriate speeds. With the carriage located at the left hand end of its travel and clear of the work piece, the high part of cam 78 will be in position to gauge the depth of the cut. Adjustment ofthe cutter by means of the wheel and head 88 will already have placed it in position to take a roughing cut of predetermined depth. Now if the controlhandle 130 is shifted to the left the reversing clutch is coupled with the gear 41 and the feed mechanism is driven in the directions indicated by the arrows on Figure 25 to shift the carriage slowly toward the right. Thus extended along the work from the starting point and the sides of the thread are gener ated to the form determined by the edge outlines of the cutter teeth. rrived at th end of the feed movement (the limits of which are variable by adjustment of the right hand trip dog 135), the clutch is shifted so as to cause reversal of the carriage feed, and at the same time the cam 78 is so turned by contact of the roll 108 with the wedging abutment 109 that its low part comes into contact with the stop roll 7 7 and the cutter-is fed enough further into the work to take a finishing out. It may be noted here that the abutments 109 and 110 are adjustable longitudinally in the bracket 111, whereby they maybe placed to bring the finishing cut feed into proper time with the reversal of the longitudinal feed.

When this reversal occurs the feed screw is turned in the o posite direction and the cutter is returned from right to left, the cutter driving worm then being moved from left to right, and the cutter being given a higher rate of rotation than that due solely to the rotation of this worm. The increase in the cutter rotation now caused by left hand traverse of the carriage and right hand traverse of the worm is equal to the decrease in the rate of cutter rotation following from endwise movements of the car- .riage and worm in the opposite direction during the roughing cut feed, whereby the equivalent character of rolling generative travel of the cutter relatively to the work is given during the finishing cut as during the roughing cut. When the carriage reaches its original starting point the clutch shifter' mechanism is tripped by the left hand trip dog 135 and reversing clutch returned to the neutral position, whereby the carriage comes to rest. Automatic means may be rovided for stopping the entire machine by shifting the driving belt oil the fast pulley at this time, if desired, but such means are not part of the present invention and are, therefore, not shown herein.

Further uses of the in/ventz'on.Modifications in the machine thus particularly described may be made, by way of additions or eliminations or changes in structure or arrangement of the several elements ofthe machine, within the fundamental principles ,of the invention and within the scope for which I claim protection. One possible modification for a specific. purpose is illus trated in Figures 20 to 22, where the machine is shown prepared for making cutters such as hobs, taps and other formed cutters which are capable of being generated. Such cutters are notched or gashed to provide cutting teeth. For making such wor ,pieces the teeth produced between the gashes or notches must be backed oif'or relieved from those ends thereof where the cutting edges are formed to give the clearance necessary in cutting tools. Such backing of? is effected by a modification of the depth feed cam 7 8 and of the means for driving it. This modified cam is shown at 78 in Figures 20 and 22 and represented as having a number ofsimilar lobes and of being driven at a predetermined rate of rotation from the work spindle 6 by means of intermesh'ing gears 138 and 139 on the work spindlefi andthe cam shaft 105 respectively'.

Assuming that the work piece 1* in this case is a hob havingeight teeth, then thenumber of lobes in the cam and the gear ratio 138 to 139 are such as to cause eight rises and descents of the cutter during each rotation of the work piece. The rises and descents of the camare so formed and arranged that the cutter is withdrawn from the axis of the work while in the open spaces or gashes of the work piece and is gradually advanced toward such axis while acting on those parts of the work which eventuallybecome teeth; In order that generative travel of the cutter may take place together with continuous rotation of the relieving cam when thework piece is to be itself a generated cutting tool, the gear 139 is preferably splined to the shaft 105 and'is restrained from endwise movement by a bracket 140; or other well known mechanical expedients for obtaining the same effect may be used. Other specific uses of the machine for turning out work of the same general character and in essentially the same way as herein described, although specifically different in detail, are within the scope of my contemplation and are intended to moving the connection between this worm and its driving pulley, or in place of the worm a cylindrical rack may be substituted. In that case the generative travel of the cutter relatively to the work is the same as already described, but the cutter is not given that increment ofrotatiofi which causes the generated rib to be helical. Other work pieces with non-helical ribs of many 1; diverse shapes in profile may be generated by essentially the same machine and in the same manner as described, with the use of appropriate cutters.

What I claim and desire to secure by Letters Patent is:

1. A thread generating machine comprising a cutter. holder, a cutter rotatably 

